Actually, I heard listening to the press conference that the investigation was honing in on that as one of the aspects that they were certainly concentrating on.
Somewhere there has been an error made either in input to the laptop, or in the laptop software (very unlikely), or in the transfer from the laptop output to the aircraft's systems, and the design of the system cross checks for such a fundamental input, whether human or computer hasn't picked it up. As I said above, a 40% difference in takeoff weight is fairly fundamental.